The opposite of occasional is frequent.
Changeable, occasional
Some words have no perfect antonyms. "Occasional" is on a scale: Always...frequently...often...occasionally...seldom...infrequently...rarely...never. There is really no opposite. For words like this, the logical answer is to add "Not". "Not occasional" is the opposite of occasional.
That is the proper spelling of the word "occasional" (infrequent).
One antonym for occasional might be 'frequent'. Persistent doesn't really seem to be a good fit here.
Infrequent, rare, occasional.
Frequent.
It could be, if occasional is used to mean as an amateur in a profession. The opposite of occasional would be frequent. Other opposites for career could be avocation or hobby.
Changeable, occasional
Some words have no perfect antonyms. "Occasional" is on a scale: Always...frequently...often...occasionally...seldom...infrequently...rarely...never. There is really no opposite. For words like this, the logical answer is to add "Not". "Not occasional" is the opposite of occasional.
The word opposite to regular is irregular.
Your diet. Lack of moisture or certain foods can be troublesome-like bananas in excess for example. Raisins, grapes, watermelon, etc. has the opposite effect. Having occasional bouts is normal, but if more than occasional, might want to look more closely at what you're eating.
An Occasional Dream was created in 1969.
Occasional Oratorio was created in 1746.
An Occasional Hell was created in 1993.
The duration of Occasional Wife is 1440.0 seconds.
An Occasional Hell has 256 pages.
Occasional Wife - 1966 My Occasional Brother's Keeper 1-27 was released on: USA: 11 April 1967